Refrigerating system



acm 5251938 2,134,409

' UNITED STATES PATENT OFFICE 2.13am a I nnrareamrme SYSTEM John Kirgan, Easton, Pa, asaignor a lngersoll Band Company, Jersey City, N. J., a corporation of New Jersey Application June 17, 1936, Serial No. 85,653

My invention pertains to refrigerating systems, I shall make clear other objects and advanand especially to a refrigerating system designed tages of the invention in the description of the to meet the requirements of all conditions of opform of the invention illustrated herein, but the on om maximum to minimum output. right is reversed to change the structure of the It is a particular object of this invention to, apparatus and mode of procedure without deprovide a refrigerating system wherein a liquid parting from the principle or scope of the invenrefrigerant is partially vaporized and chilled, tion as set forth in the appended claims. andwherein the vapor so formed is condensed, 0n t e w g Figure 1 Shows in Outline an the system being so constructed that it can be arrangement of parts according to this invention,

1o advantageously operated over the entire load and range. To this end the practical embodiment of Figures 2 and 3 present details, Figure 3 being the system comprises parts or members which a section on line 3 3 of Figure 2. can be connected and operated in several diifer- The numeral I indicates a vessel enclosing an out ways to maintain the expenditure of power evaporator chamberhaving near the top thereof substantially in proportion to the amount of an inlet header 2 with spray openings through '15 refrigerating eifect that is needed. which water or other liquid refrigerant issues in Another object of the invention is to provide the form of jets into -the chamber fro a P p condensing apparatus in such a refrigerating sys- Some vaporization of the liquid occurs, but the tem wherein the consumption of the heat-abgre ter Po t o of the refrigerant remains liquid .20 sorbing medium, such as water, for liquefying the and p s o the Ou t conduit n this 20.

vapor formed in the process of partial vaporizapipe the refrigerant is conducted to a cooling coil tion, can be much reduced when the refrigerating or other device; There the refrigerant absorbs load drops. Thus, in its preferred form, the heat and may thereafter return to the evaporator system includes an evaporator for the refrlgby way of the pipe 3.

era-nt, evacuators forremoving the vapor from g The ev p I has Outlets 5 in the p lead- 25 the evaporator and for'delivering such vapor to ing to the intakes of evacuators that both withthe condensing apparatus, the condensing appadray the vapor and maintain the proper vacuum ratus comprising several separate condensers in the chamber. The evacuators are centrifugal which may be utilized in several different ways compressors in housings 6 and I. The com- 3 to effect the desired economy of cooling medium pressors raise the pressure of the vapor formed consumption. in the chamber and force the vapor into con- A still further object of the invention is to densers 8 and 9. The compressors are each roenable the relationship between'the evaporator, tated by a separate variable speed motor [0 p the evacuators, and the condensers to be changed through s afts d Suitable S p- D gearin as desired, to aiford the greatest possible economy Each motor l0, if an electric motor, may be confor part-load operation over along period of time. nected by wires 3| to the supply wires 30, and For removing vaporized refrigerant from an in one of the wires 3| may be placed a variable evaporator a centrifugal compressor has been resistance as diagrammatically illustrated at 32, found to produce good results, because it is selffor varying the speed of each motor. It will be 40 regulating in power consumption and to a-great understood, however, that other types of motors, 40

extent self-stabilizing in function. This is charsuch as steam turbines, for example, may be acteristic of such a machine at heavy loads and utilized if desired. somewhat less, but at very light loads difficulties The two condensers may be cooled by any suitmay arise, for as the load decreases the degree able medium, such as water, supplied by a pipe of'compression demanded of the compressor bel2 and carried away therefrom by a pipe I3. 45 comes greater and the operation of the com These condensers have interior tubes through pressor tends to become unsteady and at very which the cooling medium flows while the vapor light loads is manifested by surging of the vapor of the refrigerant is being liquefied by contact in the compressor. My system of refrigeration with same. .After being condensed the vapor will is well adapted for use with a centrifugal combe conducted from each condenser throughthe pressor under'light load conditions and compipes it back into the pipe 3 or evaporator l. prises several such units connected to operate The condensers will of course be provided with in variable relation to each other and at variable suitable air removal pumps (not shown) for the speeds according to the requirements 01' any conpurpose of maintaining the desired vacuum dition that may be encountered. therein. q 55 With this apparatus different adjustments can be made for operation under heavy and light load conditions. The two compressors-can operate together at full speed, or'one may be so operated and the other may be run at reduced speed or shut down entirely, or both compressors or one alone may run at a reduced speed. A great deal of flexibility is thus secured. Thus the mass and rate of removal of the vapor extracted by each compressor can be regulated as conditions demand.

Also under some circumstances the apparatus may be required to run for long periods of time at reduced load and at the same time use a minimum supply of cooling water for the condensers. In that case the outlet flue I5 of the evacuator 8 may be coupled to the inlet neck or flue I6 of the evacuator I through a cross connection I1, and this connection may have valves to break communication between the compressor I5 and its condenser 8 and put this compressor in series with the other compressor I, which is .then disconnected from the evaporator I. The valves may be located at the junction of the cross connection with the pipes I5 and I6. Such a valve is shown at I8 having a spindle I9 at one end in suitable bearings where the flue II joins the flue I5. In one position this valve will close the flue I'I while leaving the flue I5 open, and in another position it will close the flue I5 and open 'the flue II so that the compressors are in series instead of in parallel. See Figure 2.

A similar valve element at the junction of the flue I1 and inlet neck I6 of the other compressor may be used for the same purpose 'to shut the flue I! when the compressor I is to work in parallel with the compressor 6, or to cut oil the compressor I from the evaporator I and connect the flue II to the inlet side of this compressor. Thus the one compressor I may be cut off from the evaporator I to receive the discharge of the other compressor 8, both compressors then delivering to one condenser 9 while communication is interrupted between the compressor 8 and ,con-

,denser 8. When so related the two compressors will most of the time be operated at reduced speed to save horsepower, but even at low speed in series arrangement they will produce a. considerably higher ratio of compression than would either compressor operating at full speed. That is to say, the vapor in the evaporator I is compressed toa greater extent by the two compressors in series before it reaches the condenser 8, Hence the inside pressure of the condenser 9 will be higher and the water which circulates through the condenser to cool it can be used in smaller quantity.

Tohold each valve I8 in either position, the spindle I9 has an arm 2I with a threaded bolt 22 passing through a threaded opening in its outer end. This bolt has a head 23 to serve as a knob or handle. This bolt can be screwed into threaded openings in projections 24 on the outside of the pipes I 5, I8 and I1, there being two projections at each junction at such points as I will enable each valve to close one-or the other pipe at the junction controlled by said valve.

the discharge pipe I3 of the condenser 8 to the admission pipe I2 of the condenser 8. In this case one compressor must compress the vapor to a higher pressure than the other, because the pressure in the condenser 9 will be higher. The

compressor I is therefore operated on a different part of its capacity curve and will extract somewhat less vapor from the evaporator I than the other. Hence condenser water can be saved in this instance likewise.

The connections for the changes in the arrangement are shown in Figure 1 where a length of piping 25 unites the inlet I2 of the condenser 9 to the outlet I3 ofthe' condenser 8. The pipe I2 of the condenser 8 has a shut-ofl' valve indicated at 26, and the pipes I3 and 25 have similar shut-oil valves 21 and 28 respectively. When the valve 28 is closed and the other two are open,

the two condensers operate independently. When however, the valve 28 is open and the valves in the pipes I2 and I3 are closed, then the two condensers are in series.

If the compressors are identical in design and size and run in parallel at the same speed, they now divide the single mass of vapor in the evaporator I into separate portions and compress these portions unequally. One portion is delivered by the compressor 6 to the condenser 8 and the remainder is delivered by the compressor I to the condenser 9. The cooling water in this condenser 8 will be somewhat higher in temperature than in the condenser 8. Hence the evacuator I will work against a slightlyhigher back pressure and will compress the vapor to a greater extent, although the suction pressure for each compressor is the same. .The compressor I will therefore operate on a difierent part of its capacity curve, and will extract somewhat less vapor from the evaporator than the. other compressor 6.

The water needed for the condensers may thus be diminished and operating costs cut down, while at the same time the necessary reduction in temperature of the water entering the evaporator is rendered possible. The system operates well at full load or part load. A centrifugal compressor in a refrigerating system of this type running atconstant speed, is self-regulating, that-is, the power for operating same is automatically reduced when the loadis reduced. Also the operation of the compressor is quite stable over a greater range than when it is utilized for other purposes. Generally a centrifugal compressor .will run unsteadily and the vapor will surge when the load falls to about two-thirds of the full load. In a refrigerating system as set forth above, however, the compressor load remains stable until a much lighter load is reached.

Therefore the two compressors running in parallel with the. condensers in series will cooperate at full output of the system, though the compressor I then operates at less than its total'capacity, and at part load also until the point where'surging in one compressor will begin. So thatsurging of the vapor in either compressor will not interfere with normal operation, even at relatively low load, a suitable automatic governor .or controlling device may be attached to each compressor when the condensers are in series, to take eflect at the right moment; that for the compressor I to act flrst because this compressor may attain instability of load before the other, or the compressor I may be stopped atv a selected point by switching off its motor I I] while the other compressor continues to operate.

The centrifugal compressor is virtually selfstabilizing in function because, as is well lmown with a drop in load, the water entering the evaporator is cooler, and the vapor formed is less in density but larger in specific volume. Also the pressures in the evaporator and in the condenser diminish, but the ratio of compression of the centrifugal compressor increases. The drop in pressure and density of the vapor with increase of volume and greater compression are the factors that tend to maintain the normal operation of the compressor until the load becomes small. Hence,

as the demand for refrigeration lessens, while the rated speed of the compressor continues, the power consumed by the compressor is reduced, but no loss 'of stability ensues before very light load is reached.

When the compressors 6 and I run in parallel and the condensers 8 and 9 are connected in series, the compressors can be run together at full speed, or one at full speed and the other at reduced speed, or either can be run' alone at full speed or less. When the compressor I operates alone or with the compressor 6 at any speed less than full speed of the latter, the water in the condenser 9 will not be warmed so much and therefore the temperature and pressure in the condenser 9 will be less, thereby permitting the compressor I to force the vapor into the condenser 9 more easily. The compressor 1 now will be more stable than when operating with the compressor 6 and the former runs at the full speed which can be imparted to it by its motor Ill.

An additional valve 29 may be placed in the water inlet pipe I! for the condenser 8, and any or all of the valves 26, 21, 28 and 29 may be automatically controlled in accordance with conditions in the system to control the cooling water for the condensers. Automatic regulation of the valves l8 may of course also be practiced, the valves then being arranged to operate in unison or separately in accordance with variations in load within the system. It will, of course, be clear that more than two compressors or condensers arranged in the manner shown, may be used if desired, two having been shown only for the purpose of illustration.

Thus it will be seen that the system may be operated in various ways and is readily adaptable to part load operation. The speed of the compressors may be varied and the rate of evacuation varied accordingly to partly compensate for load changes. The condensers and evacuators may be placed in various relations to each other and cooling water saved, or the relationship between the compressors may be altered to effect furthe savings in the cost of operation. a

I claim:

1. In a refrigerating system, an evaporator chamber, a plurality of evacuators for removing vapor from the chamber, condensers to which the evacuators discharge, and meansfor eliminating the communication between some of the evacuators and the chamber and for placing such evacuators in series with the other evacuators when the load on the refrigerating system drops. 2. In a refrigerating system, an,evaporator, a

plurality of evacuators for the evafporator, a separate condenser for each evacuator, connections for supplying cooling medium separately to each condenser, means for altering said connections to cause the cooling medium to pass serially through the condensers, means for selectively connecting each evacuator in series with the evaporator and its condenser or connecting the' evacuators in series with each other and with the evaporator and one of said condensers, and means for varying the operating speed of one or more of said evacuators thereby varying the rate of evacuation of said evaporator.

' 3. In a refrigerating system, an evaporator, a plurality of evacuators for the evaporator, condensers to which the evacuators discharge, and means for varying the relationship between the evaporator, evacuators, and condensers to maintain the consumption of power in the system substantially proportionate to the load thereon, said means being positioned to arrange some of theevacuators selectively in parallel or in series with each other with respect to their connection to the evaporator.

4. In a refrigerating system, an evaporator, a plurality of vapor evacuators for the evaporator, a separate condenser for each evacuator, and means for selectively directing the flow of vapor from the evaporator in parallel streams through each evacuator into its condenser or directing such flow in one stream through the evacuators in series and into one'of the condensers.

5. In a refrigerating system, an evaporator, a plurality of evacuators for the evaporator, a separate condenser for each evacuator, means for alternativelylconnecting the outlet of one evacuator to its condenser or to the inlet of a second evacuator, and means for alternatively connecting the inlet of said second evacuator to the evaporator or to the outlet of said one evacuator.

6. In a refrigerating system, an evaporator, a plurality of evacuators for the evaporator, a separate condenser for each evacuator, a conduit connection between the outlet of one evacuator and the inlet of a second evacuator, valve means at one end of the connection to alternatively connect the outlet of said one evacuator to its con-' denser or to said connection, and valve means at the other end of said connection to alternatively connect the inlet of said second evacuator to the evaporator or to said connection.

7. In a refrigeratingsystem, an evaporator, a plurality of evacuators for the evaporator, separate means for each evacuator to condense vapor discharged therefrom, and means for selectively connecting the evacuators in series with each other and with the evaporator and one of said separate condensing means.

" v JOHN KIRBAN. 

